Assessment of Oxidative Stress Index in Sub-clinical Hypothyroidism

Oxidative stress caused by reactive oxygen species (ROS) causes an imbalance in the antioxidant/oxidant status of an individual It is well recognized in hyperthyroidism & overt hypothyroidism but not in subclinical hypothyroidism. SCH has recently attracted much attention as it exhibits the same cardiovascular consequences as overt hypothyroidism. The main objective of the study was to evaluate the oxidative stress index (OSI) and correlation of OSI with thyroid profile and Paraoxonase-1 (PON-1) the antioxidant enzyme associated with HDL in subjects with subclinical hypothyroidism. OSI was calculated after measuring the total oxidant status (TOS) and total antioxidant status (TAS). This cross-sectional study included 64 subjects with sub-clinical hypothyroidism, and 128 subjects with normal thyroid profile between 25 and 75 yrs of age. Differences between the variables in the two groups were analyzed by the unpaired t test. Correlation analysis was done by Pearson's test. Subjects with SCH showed significant increase in oxidant status and oxidative stress index. There was no significant change in the antioxidant status as well the PON-1 activity in subjects with SCH. OSI can be considered as an efficient marker of oxidative stress. Its diagnostic ability was assessed by ROC Curve which gave a significant sensitivity and specificity.